This invention relates to semiautomatic and automatic firearms and more particularly to buffers therefor. The invention also relates to automatic firearms which incorporate a means to reduce the rate of fire during automatic operation.
It has been found that in most automatic firearms, it is necessary to cushion the load imparted to the frame of the firearm by the sudden stoppage of movement of the bolt and carrier assembly at the termination of recoil. This is usually accomplished by providing a resilient buffer at the rear of the bolt and carrier assembly or at the end of the receiver. Various forms of buffers are known in the art. For example, the buffer may travel with the bolt and carrier assembly or be fixedly mounted in the receiver. An example of the former is shown in U.S. Pat. No. 3,366,011. The buffer of this patent is in current use in the M-16 rifle and serves a dual function in that it not only cushions the impact at the termination of recoil, but also prevents rebound or bounce of the bolt carrier of the bolt and carrier assembly after it slams into the breech end of the barrel. As discussed in detail in the patent, such rebound can prevent adequate firing pin protrusion from the bolt face.
Hydraulic buffers which serve to reduce the rate of fire of automatic weapons are known in the art. One such buffer includes a directly spring loaded piston which must first compress its spring before encountering hydraulic resistance from the fluid which fills only a portion of the piston's chamber, the remaining portion being occupied by air. A disadvantage of this buffer is that it does not provide immediate hydraulic retardation and that the air therein is heated by compression, in addition to causing foaming of the hydraulic fluid.